The rate of salt and sugar into pickled cabbages was determined, and physicochemical characteristics, such as sensory, texture, and pH, of vinegar pickled cabbages during storage were examined at different storage temperatures and vinegar concentrations. The rate of salt and sugar penetration was faster in smaller size and on leaves rather than the stem of cabbage. Also, higher salt and sugar concentration and higher storage temperatures led to increase in salt and sugar permeation rate. As a result of sensory test, lower storage temperature is the most suitable, and 6% vinegar concentration was the mostly appropriate. Hardness and cohesiveness were decreased significantly at the initial 1st week storage time, but storage temperature did not show any significant effect. Addition of vinegar contents enhanced the hardness, but decreased cohesiveness. The pH was lowered with increasing vinegar content, indicated most significant factor on pickled cabbage. In general, salt and sugar contents rather than storage temperature have greater influence on permeation rate, and especially, addition of vinegar affects the texture of pickled cabbage.

Recently, graphene oxide (GO) has been extensively investigated for gas and liquid separation because thin-film GO membranes show quite interesting separation performance. However, even GO membranes exhibit relatively low gas permeability due to high tortuosity caused by high aspect ratio of GO. Normally, the size of GO is in the range from a few hundred nanometers to a few micrometers, so inherent gas permeability would be very varied. For practical applications of GO membranes, the gas permeability should be improved. As such, in this study, we have modified the pristine GO sheets to reduce the gas permeation pathway, with maintaining GO’s excellent gas separation properties. This study will provide a further insight on how such two-dimensional nanosheets can be used for membrane applications, competing with existing membrane materials.

It is well known that the membrane permeation in pervaporation is governed by both the chemical nature of the membrane material and the physical structure of the membrane and also the separation can be achieved by differences in either solubility, size or shape. The solubility of the penerrant in the polymeric membrane can be described qualitively by applying the Hildebrand relation [1] which relates the energy of mixing of the penerrant and the polymer material. Froehling et al. have tried to predict the swelling behavior of polymers for the systems of polyvinylchloride(PVC)-toluene-methanol, PVC-trichloroethylene-nitromethane and PVC-n-butylacetate-nitromethane[2]. The former two systems which do not show the donor/acceptor interactions upon mixing showed the successful results[2]. In addition to this technique, there are several other possible approaches to predict the swelling behaviors of polymers, such as the surface thermodynamic approach[3, 4], the comparison of the membrane polarity with the solvent polarity in terms of Dimroth's solvent polarity value[5].